Solenoid Coils: The purpose of a solenoid valve coil is to convert electrical energy into linear motion. The coil consists of copper wire (or aluminum) wound around a hollow form. When electric current flows through the coil, a magnetic field is created. This is accomplished by placing a ferromagnetic core inside the coil. In a solenoid valve, the ferromagnetic core is called the valve plunger. When the current flows through the coil, the lines of magnetic flux turn the plunger into an electromagnet. The magnetic field causes the plunger to slide further up into the coil, opening the valve body orifice or pilot orifice.
Solenoid Valve Coils and Electrical Polarity
A common question about solenoid valve coils is whether the electrical current polarity matters in a DC coil. Most coils with lead wires use the same color wire for both terminals and have no polarity markings. The answer is that polarity does not matter. You can connect the positive terminal to either of the two wires without affecting the operation of the valve.